The proposed study seeks to examine conventionalized and spontaneous sign lowering in American Sign Language (ASL), which are forms of phonetic reduction that occur in fluent signing. Although a sign's location on the body is a phonological parameter that differentiates it from other signs, location can be extremely variable at a phonetic level. For instance, particular signs that are produced at the forehead or temple in citation form are conventionally lowered in fluent signing to phonologically-distinct locations (e.g., the jaw). Lowering also occurs spontaneously in other signs located at the forehead or temple, when there is increased signing speed or coarticulatory pressure. The goal of this study is to compare these two phenomena, conventionalized and spontaneous sign lowering, and analyze the frequency of their occurrence and their physical extent and shape as an effect of speed and phonetic context. Kinematic data will be collected from native ASL signers as they produce signs that are located at the forehead or temple in citation form. Signing speed and sign context will be manipulated in order to increase the occurrence and extent of both conventionalized and spontaneous sign lowering. We propose that both the occurrence and extent of phonetic lowering are influenced by a sign's articulatory structure, and this is what allows a sign to be lowered and yet remain intelligible as the same sign. In particular, based on the specific cases of conventionalized sign lowering that have been documented, we predict that signs with a simple path movement to the head will move to lower locations on the head, whereas signs that include an additional sign-internal movement will become dissociated from the head and be produced in the signing space in front of the body. This study examines signed language within the framework of articulatory phonology, with the aim of understanding the nature of articulatory targets and gestures in the sign modality. Project Narrative: This study is relevant to NIH's public health mission, because it contributes to the development of physiologically-based measures of sign production and perception, which in turn will help differentiate normal phonetic variation in sign production from variation due to language or motor disorders in Deaf signers. Further, it provides a unique context for analyzing targeted limb movements, which is relevant to the understanding of human motor disorders.